The catecholamine response to acute myocardial infarction: effect of early administration of sotalol

Effect of early treatment with anti-hypertensive drugs on short and long-term mortality in patients with an acute cardiovascular event

BACKGROUND

Acute cardiovascular events represent a therapeutic challenge. Blood pressure lowering drugs are commonly used and recommended in the early phase of these settings. This review analyses randomized controlled trial (RCT) evidence for this approach.

OBJECTIVES

To determine the effect of immediate and short-term administration of anti-hypertensive drugs on all-cause mortality, total non-fatal serious adverse events (SAE) and blood pressure, in patients with an acute cardiovascular event, regardless of blood pressure at the time of enrollment.

SEARCH STRATEGY

MEDLINE, EMBASE, and Cochrane clinical trial register from Jan 1966 to February 2009 were searched. Reference lists of articles were also browsed. In case of missing information from retrieved articles, authors were contacted.

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing anti-hypertensive drug with placebo or no treatment administered to patients within 24 hours of the onset of an acute cardiovascular event.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed risk of bias. Fixed effects model with 95% confidence intervals (CI) were used. Sensitivity analyses were also conducted.

MAIN RESULTS

Sixty-five RCTs (N=166,206) were included, evaluating four classes of anti-hypertensive drugs: ACE inhibitors (12 trials), beta-blockers (20), calcium channel blockers (18) and nitrates (18). Acute stroke was studied in 6 trials (all involving CCBs). Acute myocardial infarction was studied in 59 trials. In the latter setting immediate nitrate treatment (within 24 hours) reduced all-cause mortality during the first 2 days (RR 0.81, 95%CI [0.74,0.89], p<0.0001). No further benefit was observed with nitrate therapy beyond this point. ACE inhibitors did not reduce mortality at 2 days (RR 0.91,95%CI [0.82, 1.00]), but did after 10 days (RR 0.93, 95%CI [0.87,0.98] p=0.01). No other blood pressure lowering drug administered as an immediate treatment or short-term treatment produced a statistical significant mortality reduction at 2, 10 or >/=30 days. There was not enough data studying acute stroke, and there were no RCTs evaluating other acute cardiovascular events.

AUTHORS' CONCLUSIONS

Nitrates reduce mortality (4-8 deaths prevented per 1000) at 2 days when administered within 24 hours of symptom onset of an acute myocardial infarction. No mortality benefit was seen when treatment continued beyond 48 hours. Mortality benefit of immediate treatment with ACE inhibitors post MI at 2 days did not reach statistical significance but the effect was significant at 10 days (2-4 deaths prevented per 1000). There is good evidence for lack of a mortality benefit with immediate or short-term treatment with beta-blockers and calcium channel blockers for acute myocardial infarction.

Urinary catecholamines and metabolites in the immediate postoperative period following major surgery

BACKGROUND

Induction of anaesthesia can precipitate catecholamine release from an undiscovered pheochromocytoma and induce a hypertensive crisis. However, it is assumed that catecholamine and metabolite values resulting from the effects of surgery per se in the early postoperative period would overlap with the values generated by a tumour, and it is not known how soon after biochemical investigations can be carried out.

AIM

To study patterns of urinary catecholamine excretion and the feasibility of biochemical screening for phaeochromocytomas in the immediate postoperative period in otherwise healthy subjects undergoing a single type of major surgical procedure.

METHODS

Catecholamines and metabolites were measured for each mole of creatinine in single voided urine on one preoperative and four postoperative days in five subjects who underwent elective coronary artery bypass graft surgery with an uncomplicated postoperative course. Reference ranges were established from 33 healthy normotensive volunteers.

RESULTS

Excretion of adrenaline, noradrenaline, dopamine, vanillylmandelic acid, and metadrenaline was within normal limits. Normetadrenaline excretion was mildly raised in four patients, but did not exceed 1.5 times the upper reference limit, and returned to normality by the fourth postoperative day.

CONCLUSION

It is feasible to perform simple urinary screening for possible phaeochromocytoma in the immediate postoperative period.

The contracted plasma volume syndromes (relative polycythaemias) and their haemorheological significance

Relative polycythaemia is a general term which includes patients with a normal red cell mass but a contraction of the plasma volume as the cause for the polycythaemia. The relative polycythaemias can broadly be divided into two groups. Firstly, relative polycythaemia may be due to a primary loss of plasma volume due to dehydration, capillary leak or hypo-oncotic pressure. Secondly, relative polycythaemia may be due to a primary contraction of the vascular compartment (i.e. reduced venous compliance). It is this second group which is the least understood and is analysed in detail in this review. In general, this group of polycythaemias is secondary to exogenous or endogenous stress and is mediated via the sympathetic nervous system. Hypoxia, smoking, neurological disorders, myocardial infarction and acute psychological stress have all been demonstrated as possible factors. In many cases of chronic stress polycythaemias aetiological factors may be identified, whereas in others the term idiopathic is probably appropriate. There appears to be a relationship between the idiopathic stress polycythaemias, hypertension and psychological stress. Other patients may have primarily a disorder of blood volume control involving the autonomic nervous system and its receptors. The haemorheological significance of relative polycythaemia and its management are discussed. Treatment is generally dictated by the underlying cause. In stress polycythaemias the stimulus should be removed as far as possible. However, in some patients with chronic idiopathic stress polycythaemia, regular venesection may be required to maintain the venous haematocrit at an appropriate level.